Agenda - Public Works Committee - 11/15/2022

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No man-made materials were observed. The DNR provided information on their records for the nonnal water level of the wetland. This information was used to guide the design of the outlet. Timeframe: The presentation is anticipated to take 10 minutes. Observations/Alternatives: Staff met with Wes Saunders -Pearce, DNR North Metro Area Hydrologist, on October 25 and discussed the plans. He liked the plans and that the City is moving towards providing a permanent outlet structure for Wetland 114P. He asked for some additional information to be provided with the plans. The DNR normal water level for the wetland was recorded using the NGVD29 datum. The current elevation datum is NAVD88. Staff contacted a surveyor that has done work for the City and asked what the correction factor is to convert from NGVD29 to NAVD88. The NAVD88 is 0.34 ft higher than NGVD 29. THe DNR provided a normal water level of 858.1. Staff is proposing using this elevation based on NAVD88 which will result in the water level of the wetland being 0.34 ft higher than when the DNR recorded the elevation. The DNR also asked for the hydrology model for the wetland and drainage basin. The 2-year elevation is 856.8 ft, 0.5 ft above the normal elevation. The 10-year elevation is 859.8 ft, 0.8 ft above normal elevation. The 100-year elevation is 859.6 ft, 1.5 ft above normal elevation. The rims of the existing sanitary manholes in the project area will be set at 860.6 ft, 1 foot above the 100-year elevation. We also discussed timing for the DNR permit that is required to modify the outlet elevation. The DNR Permit can take up to 60 days from submittal of the application to receipt of the permit. Raising the sanitary sewer manholes is planned for late January/early February to take advantage of frozen conditions to allow access to the structures. Mr. Saunders -Pearce recommended submitting the application soon to allow time for processing. He indicated the application can be updated during the review process. Funding Source: The funding source will be the Stormwater Utility Fund. The Engineers Estimate for this project is $27,000. Recommendation: Staff recommends bringing the project to the December 13, 2022 City Council meeting for authorization to advertise the project to receive quotes for the work. Action: Motion to recommend the City Council authorize advertising for quotes for this project. Estimate Plans Attachments Form Review Inbox Reviewed By Date Bruce Westby Bruce Westby 11/10/2022 02:31 PM Brian Hagen MayJo Warner 11/10/2022 02:40 PM Form Started By: Len Linton Started On: 11/09/2022 01:57 PM Final Approval Date: 11/10/2022